Oil and gas wells produce crude oil, natural gas and/or byproducts from subterranean petroleum reservoirs. Petroleum reservoirs, such as those containing oil and gas, typically include finite-dimensional, discontinuous, inhomogeneous, anisotropic, non-elastic (DIANE) rock formations. Such formations, in their natural state (prior to any fracture treatment), are characterized by natural fractures and faults of various sizes, shapes and orientations.
During a fracture treatment, fluids are pumped under high pressure into a rock formation through a well bore to further fracture the formations and increase permeability and production from the formation. The fracture growth is affected by the interaction between propagating hydraulic fracture and natural fracture. When net pressure of the fluid in an induced hydraulic fracture exceeds a critical net pressure (equal to the difference between the maximum and minimum horizontal stress), leakoff through natural fractures occurs. This leads to dilation of natural fractures and subsequently formation of complex fracture networks. Thus complex-fracture patterns can include networks of fractures that extend to the well bore, along multiple azimuths, in multiple different planes and directions, along discontinuities in rock, and in multiple regions of a reservoir.
Hydraulic fracturing treatment often is implemented as part of well completion in shale oil/gas field development. The fracturing treatment can be implemented, e.g., in a horizontal well and in multiple stages. Post fracturing, in addition to induced hydraulic fractures, the dilated natural fractures can provide additional pathways for hydrocarbon migration and hence production. Enhancing the fracture-formation area through complex fracture networks can improve fracturing treatment in shale reservoirs.
Several fracture monitoring tools such as microseismics, pressure analysis, and tracers are available to characterize the distribution of fractures and post-frac conductivity. Good data acquisition and interpretation can improve reliability of fracture diagnostics techniques.
Like reference numbers and designations in the various drawings indicate like elements.